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Commit b971e7ac authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: fix /proc/net/snmp as memory corruptor 



icmpmsg_put() can happily corrupt kernel memory, using a static
table and forgetting to reset an array index in a loop.

Remove the static array since its not safe without proper locking.

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 013cd397

net/ipv4/proc.c

+30 −28
Original line number Diff line number Diff line
@@ -237,43 +237,45 @@ static const struct snmp_mib snmp4_net_list[] = { 
	SNMP_MIB_SENTINEL

};



static void icmpmsg_put_line(struct seq_file *seq, unsigned long *vals,

			     unsigned short *type, int count)

{

	int j;



	if (count) {

		seq_printf(seq, "\nIcmpMsg:");

		for (j = 0; j < count; ++j)

			seq_printf(seq, " %sType%u",

				type[j] & 0x100 ? "Out" : "In",

				type[j] & 0xff);

		seq_printf(seq, "\nIcmpMsg:");

		for (j = 0; j < count; ++j)

			seq_printf(seq, " %lu", vals[j]);

	}

}



static void icmpmsg_put(struct seq_file *seq)

{

#define PERLINE	16



	int j, i, count;

	static int out[PERLINE];

	int i, count;

	unsigned short type[PERLINE];

	unsigned long vals[PERLINE], val;

	struct net *net = seq->private;



	count = 0;

	for (i = 0; i < ICMPMSG_MIB_MAX; i++) {



		if (snmp_fold_field((void **) net->mib.icmpmsg_statistics, i))

			out[count++] = i;

		if (count < PERLINE)

			continue;



		seq_printf(seq, "\nIcmpMsg:");

		for (j = 0; j < PERLINE; ++j)

			seq_printf(seq, " %sType%u", i & 0x100 ? "Out" : "In",

					i & 0xff);

		seq_printf(seq, "\nIcmpMsg: ");

		for (j = 0; j < PERLINE; ++j)

			seq_printf(seq, " %lu",

				snmp_fold_field((void **) net->mib.icmpmsg_statistics,

				out[j]));

		seq_putc(seq, '\n');

		val = snmp_fold_field((void **) net->mib.icmpmsg_statistics, i);

		if (val) {

			type[count] = i;

			vals[count++] = val;

		}

		if (count == PERLINE) {

			icmpmsg_put_line(seq, vals, type, count);

			count = 0;

		}

	if (count) {

		seq_printf(seq, "\nIcmpMsg:");

		for (j = 0; j < count; ++j)

			seq_printf(seq, " %sType%u", out[j] & 0x100 ? "Out" :

				"In", out[j] & 0xff);

		seq_printf(seq, "\nIcmpMsg:");

		for (j = 0; j < count; ++j)

			seq_printf(seq, " %lu", snmp_fold_field((void **)

				net->mib.icmpmsg_statistics, out[j]));

	}

	icmpmsg_put_line(seq, vals, type, count);



#undef PERLINE

}